A method of the aforementioned type is described in DE 30 42 312 C2. From a metal sheet is punched a circular blank and a cup-shaped preform is produced, e.g. by deep-drawing or spinning. The cup-shaped preform with a radial hub area and a cylindrical area virtually perpendicular thereto and coaxial to a longitudinal axis has a uniform wall thickness. The preform is fixed in a spinning device and the cylindrical area is exposed to an axial pressure, while supported on a centrally mounted block, in order to bring about a "partial collapse" i.e. a radial outward bulging from the inside to the outside. A sought material accumulation for forming a grooved bed is consequently possible through a shortening of the cylindrical area. The circular blank or the cylindrical area of the cup-shaped preform must therefore be constructed with a corresponding length.
The radial bulging out is to be obtained by rolling of a pair of rollers, which are movable axially to one another and when in engagement define an approximately arcuate recess. In the case of an axial compression, the material of the cylindrical area collapses into said recess. With the aid of correspondingly constructed support areas before or during the axial compression and collapse, an inner flange is formed between the hub area and cylindrical area, as well as an outer flange on the free end of the cylindrical area and are directed radially outwards.
The collapsed, cylindrical area is then flattened, leading to a material thickening. With the aid of a profile roller and a central support block, as well as limiting chuck and spinning mandrel halves, a V-shaped profiling of the thickened area is carried out.
This method is particularly complicated from the machinery standpoint and leads to corresponding manufacturing costs.
In a method described in EP 0 343 314 B1, a bordering roll is radially infed directly onto a circular metal blank without forming a cup-shaped preform. The bordering or curling roll has a semicircular recess and brings about a corresponding rolling in of the blank edge. Subsequently, using a spinning roll, from the bordering is formed a cylindrical wall area with a wall thickness greater than that of the hub area. In this method an inner flange and an outer flange can only be constructed after flattening. The production of poly-V-pulleys with a toothed reference mark sensor on an outer flange is not possible.
The journal "Machinery and production engineering" of 26 Jan., 1977 discloses a method for the manufacture of a toothing on the end face of a rotationally symmetrical body. A circular blank is fixed in a spinning device and is frontally upset with radially infeedable spinning rolls. The spinning rolls are provided with a depression, which has an arcuate base surface between parallel walls. The material of the end region of the circular blank is forced into the depressions of the spinning rolls. The material displacement leads to a terminal thickening, which can be symmetrical, i.e. projecting uniformly to either side of the blank, or asymmetrical, i.e. projecting only to one side. A toothing is then performed on the thickened area.